Speaker
J. Matthew Durham
(Los Alamos National Laboratory)
Description
We present new results of a completed analysis from PHENIX of $\psi'$
modification at midrapidity in 200~GeV $d$$+$Au collisions. Strong
differential suppression of the $\psi'$ relative to the $J/\psi$ is
observed. This has also been reported recently by ALICE at forward and
backward rapidity in 5.0~TeV $p$$+$Pb collisions. In all cases the
differential suppression is too strong to be explained by nuclear
breakup effects, due to the short nuclear crossing times. Given the
observation of long range correlations in $p(d)$$+$A collisions at LHC
and RHIC, consistent with hot matter effects, these observations raise
very interesting questions about the mechanism of $\psi'$ suppression
when it is produced in a nuclear target.
In 2012, the PHENIX Collaboration installed the FVTX, a Silicon
Tracker that precisely measures the pair opening angle prior to any
multiple scattering in the muon arm absorber and thus provides an
improved dimuon mass resolution. The FVTX also allows the $\psi'$ to
be separated from the $J/\psi$ at forward and backward rapidity.
During the 2012 data taking run, the PHENIX Collaboration collected a
high statistics data sample of $p$$+$$p$ and Cu$+$Au collisions. We
present new results on the $\psi'$ from this dataset.
| On behalf of collaboration: | PHENIX |
|---|
Author
J. Matthew Durham
(Los Alamos National Laboratory)
